Centrifugal filter and separator



` `A151111 11, 1939. I J H WLLAR 2,153,581

CENTRIFUGAL FILTER AND SEPARATOR original Filed June 5, 1955 Patented Apr. 11, 1939 UNITED STATES PATENT OFFICE CENTRIFUGAL FILTER. AND SEPARATOR James Hill Millar, Dublin, Irish Free State, as-

signor to Arthur Guinness, Son and Company Limited, London, England June 22, 1934 7 Claims.

This invention relates to the centrifugal filtration and separation of liquids its object being to provide apparatus for this purpose.

According to this invention I provide a centrifugal lter and separator in which the centrin fuge bowl comprises a charging chamber and a collection chamber, a gauze or like member separating said chambers and adapted to form a support for a filter medium or substance through which the liquid to be filtered passes under centrifugal action and means in the collection chamber for collecting the filtered liquid. More particularly the centrifugal filter and separator is characterised by a lter pulp being centrifugally applied to a gauze apron, or equivalent support, in the centrifuge, said support being carried therein in such manner as to separate the location of the filter from the location of a collector for the filtered and separated liquid, the support being so constructed and arranged in relation to its carrier and to the wall of the centrifuge bowl as to avoid uneven flow of, or short-circuiting of the liquid through the filter. The filtered liquid and (or) sludge may be collected from the centrifuge bowl by means of a collector comprising a conduit having a mouth of streamlined cross section adapted to be immersed in the spinning liquid.

The accompanying drawing shows, by way of example, centrifugal apparatus for filtering and separating liquids in accordance with this invention.

Fig. 1 is a part sectional elevation of a filtering and separating centrifuge in accordance with the invention.

Fig, 2 is a plan View corresponding to Fig. l.

Fig. 3 is an enlarged sectional viw of a portion of the filtering and separating centrifuge illustrated at Fig. 1.

Figs. 4 and 5 are respectively enlarged plan and end views of the collector blade for collecting ltered liquid and also for collecting sludge from the centrifuge.

Referring to the drawing:

The centrifuge shown at Figs. l to 3 has a bowl I2 rotatably mounted within a casing and adapted to be driven by a motor arranged within the casing 2. The bowl I2 is divided into two chambers or compartments, a charging chamber I2b charged through the pipe I'I and a collection chamber I2a by means of a horizontal diaphragm or inwardly projecting ring or plate I3 having clearance gaps (obtained by means of distance pieces I3a and constituting conduit means effecting communication betweenl the bottom and top of the plate I3) between its outer edge and the inner surface of the bowl I2 said plate preventing the return of filteredliquid fromr the collection chamber I2a, to the charging chamber I2b. A gauze apron I4 is provided below the said diaphragrn or plate I3, with a narrow vertical passage between it and the inner surface of the bowl, which passage may be considered as part of the collection chamber I2a. The upper edge of the apron I4 is attached to and carried by Va depending ring I3b on the outer edge of the plate I3. The ring I3b extends downwards a predetermined distance (approximately as shown) below the under side of the ring or plate I3.

The filter material, indicated at I6, is fed with a suitable carrier liquid, into the lower or charging chamber I2b of the bowl I2 through a hopper I8 and pipe I8a, being applied to the gauze apron I4 by centrifugal action and, preferably, the filtering material `employed consists of a layer of pulp with a suitable adsorptive constituent. By varying the speed of the centrifuge and the nature and proportions of the filter pulp I6, it is possible to obtain the required filtration of liquids or semi-liquids differing in character. The greater the speed the greater is the centrifugal pressure on the pulp which is thus rendered more compact. Too high a speed will tend to block the filter medium at or near its surface, whereas the correct speed conditions are such that the adsorptive power of the medium operates throughout the greater part of the filter mass. On the other hand, a loose filter medium allows too high a speed of passage of the liquid, and imperfect separation takes place. The lter material extends from the plate I3 to the bottom of the bowl I2 and blocks the narrow gap I5 between the ring I5a. and the ring |511 at the foot of the gauze. Thus the liquid is constrained to pass through the filter in passing from the charging chamber to the collection chamber and short circuiting and uneven flow are prevented and effective filtration is ensured.

When the filtered liquid, passed by centrifugal action through the filter I6, reaches the back of the gauze apron I4 it has a free passage behind same and can pass upwards past the ring or plate I3 through the aforesaid gaps or conduit means to the upper or collection chamber I2a where centrifugal separation is effected and collection of the filtered and separated liquid can be obtained by means of a collector 4. When the filtered and separated extract has been drawn off, the sludge remaining in the centrifuge can, while the centrifuge is running, be removed by means of a similar collector of larger dimensions. The collector 4 comprises a hollow flat blade with sharpened leading and trailing edges 4b, 4a. It

has been found that this shape reduces splashing to a minimum, the entrance to the collector being submerged in the liquid While collecting to prevent inclusion of air and formation of froth and being provided with inclined collecting vanes 4c. The collector 4 is shown at Fig. 2 controlled by screw control gear consisting of a screw "I, a bracket or carrying member 6 which engages the screw I and an operating wheel 9. The scale I I is provided to regulate movement of the collector 4 so that its collecting mouth may be kept submerged in the liquid tothe desired extent.

The plate I3 being located at the top of the bowl I2 ensures that the collection chamber I2a is located above the level of the liquid in the charging chamber and hence gives rise to a gravitational head of liquid opposing the centrifugal force which forces the filtered liquid up the passage. This, together with the narrowness of the vertical passage ensures that the filtered liquid remains coherent and there is no aeration and consequent frothing.

The centrifugal apparatus described will give sharp separation of an extract from insoluble matter following eflicient filtration, as described in my co-pending application No. 25,216 led on June 6, 1935, of which this application is a division, and isy particularly adapted for use in the process described therein.

I claim:

1. A centrifugal filter and separator for use in the manufacture of food extract from brewers yeast, comprising a centrifuge bowl, driving means therefor and collecting means for the filtered liquid, said bowl comprising a container, an internally projecting annular plate thereon in spaced relationship to the wall of said container, a cylindricalgauze member depending from said plate in spaced relationship to thesaid wall, and a filter pulp of asbestos and cellulose supported on said gauze, and said collecting means comprising a conduit located above said plate and having a mouth of elongated cross section with sharp leading and trailing edges adapted to be immersed in the spinning filtered liquid with the major axis lying substantially in the direction ofmovement of the liquid.

2. A centrifugal filter and separator for use ln the manufacture of food extract from brewers yeast, comprising a centrifuge bowl, driving means therefor and collecting means for the filtered liquid, said bowl comprising a container, an internally projecting annular plate thereon in spaced relationship with regard to the container wall, a ring depending from said plate in spaced relationship to the said wall, a cylindrical gauze member depending from said ring in spaced relationship to said wall and a filter pulp of asbestos and cellulose on the inner side of said gauze, and said collecting means comprising a conduit located above said plate and having a mouth of elongated cross section with sharp leading and trailing edges adapted to be immersed in the spinning filtered liquid with its major axis substantially parallel to the direction of movement of the liquid.

3. A centrifugal filter and separator for use in the manufacture of food extract from brewers yeast, comprising a centrifuge bowl, consisting of a charging chamber and a collection chamber, driving means for said bowl and collecting means for the filtered liquid, an internally projecting annular plate on said bowl in spaced relationship to the inner wall thereof, a ring depending from said plate in spaced relationship to the said wall, a cylindrical gauze member depending from said ring in similar relationship to said wall and a filter pulp of asbestos and cellulose on said gauwand said collecting means comprising a conduit located above said plate and having a mouth of liattened cross section with sharp leading and trailing edges, said mouth being adapted to be immersed in the spinning filtered liquid which passes through said gauze and up the space between same and the said inner wall to the collection chamber above said plate, and means for adjusting the degree of immersion of the said mouth in the said liquid.

4 A centrifugal lter and separator for use in the manufacture of food'extract from brewers yeast, comprising a centrifuge bowl, driving means therefor and collecting means for the filtered liquid, said bowl comprising a container, an internally projecting annular plate thereon in spaced relationship with regard to the container wall, a ring depending from said plate in spaced relationship to the said wall, a cylindrical gauze member depending from said ring in similar relationship to said wall and a filter pulp of asbestos and cellulose supported on the inner side of said gauze, and said collecting means comprising a conduit located above said plate and having a mouth of elongated cross section with sharp leading and trailing edges adapted to be immersed wholly in the spinning filtered liquid, the major axis of the cross section lying in the direction of movement of the liquid which passes through said gauze and up the space between same and the containerl wall to above said plate, screw means for adjusting the position of said conduit and means for indicating the degree of adjustment. 1

5. A centrifugal filter and separator including a centrifuge bowl and collecting means for the filtered liquid, said bowl comprising a container and a gauze member supported in spaced relationship to the wall of said container and adapted to support a filter pulp, and said collecting means comprising a conduit located above the space between said wall and the gauze member and having a mouth of elongated cross section with sharp leading and trailing edges adapted to be immersed in the spinning filtered liquid with the major axis lying substantially in the direction of movement of the liquid.

6. A centrifugal filter and separator comprising a centrifuge bowl, driving means therefor and collecting means for the ltered liquid, said bowl comprising a container, an internally projecting annular plate thereon in spaced relationship to the wall of the container, a finely apertured member depending from said plate in closely spaced relationship to the wall of the container, a filter medium supported on said member, said collecting means being located above said plate and comprising a conduit terminating in a part of flattened cross section with a collecting mouth of similar cross section having a major axis, said mouth having varies therein lying transversely of the major axis and so inclined that they form an obtuse angle with the surface of the approaching liquid.

7. A centrifugal filter and separator including a centrifuge bowl with division means dividing it into a lower charging and an upper collection chamber, driving means therefor and collecting means in the collection chamber for the filtered liquid, said division means comprising an internally projecting annular member supported on the inner wall of the container, conduit means adjacent the said Wall and effecting communication between the bottom and top of said member, a gauze member supported from said member in closely spaced relationship to the container Wall to form a narrow vertical passage communicating with said conduit means, a filter pulp sup- 10 ported on said gauze and extending from the underside of said internally projecting member downwards into contact with imperforate means at the foot of the gauze, said imperforate means and said annular member preventing liquid passing from the charging chamber to the collection chamber without passing through the gauze, up the narrow vertical passage and through said conduit means in the annular member into the collection chamber.

JAMES I-IILL MILLAR. 

